topic. >> and just quickly, elise, the words he used specifically, that the united states will, quote, do what we must, do what we must to prevent iran from obtaining a nuclear weapon. is that ostensibly different from what we heard before? did he move at all in his position, at least in this particular speech? >> reporter: i think the rhetoric is a lot tougher, do what we must. it's the same thing, let's face it, as all options on the table. they both mean the same thing. that means if the u.s. were forced to engage in some kind of military activity, it would, but i think president obama, secretary of state hillary clinton, everyone has made clear they do not prefer that option, that they think that there's a need for diplomacy, but no one should make any mistake. if the time came and he had to make a choice between an iranian nuclear weapon and going after it, perhaps with u.s. military force, that he would do that, but clearly he's made clear he doesn't want to go there.